The present invention relates, in general, to a bulb-type LED lighting apparatus and, more particularly, to a bulb-type LED lighting apparatus that can remove heat accumulated in a space defined within a heat dissipating frame by dissipating heat upward, downward, leftward and rightward and can remove heat of the heat dissipating frame using a cooling module, thereby maximizing cooling efficiency and realizing an improvement in the expected life span and operational reliability of products.
Generally, light emitting diodes (LED) are widely used as efficient light sources in billboards, signboards, lighting apparatuses, etc. because LEDs have small sizes and long life spans, and use small amounts of electricity due to their characteristic of directly converting electric energy into light energy, and realize improved optical efficiencies compared to conventional light sources.
Further, the LEDs may be semi-permanently used due to their electrical efficiency and power saving effects, so such LEDs can realize improved durability of products. Further, LED lighting apparatuses may be configured to illuminate using a plurality of high power white LEDs, so the LED lighting apparatuses using the high power white LEDs are advantageous in that the intensity of illumination of the LED lighting apparatuses can be variously controlled by changing the number of high power white LEDs and by controlling the electric currents supplied to the LEDs, thereby realizing greatly improved marketability and operational reliability of products.
However, the LEDs typically generate a large amount of heat due to high electric current passing through their chips to produce high luminance, so LEDs are problematic in that the optical characteristics of LEDs under high temperatures may deteriorate. Thus, to constantly retain predetermined optical characteristics of LEDs, it is required to efficiently dissipate heat generated from the LEDs. When inefficient dissipation of heat generated from LEDs occurs, the optical characteristics and the expected life spans of the LEDs may be reduced. Accordingly, it is required to efficiently dissipate internal heat generated from both LEDs and LED circuit boards to which the LEDs are mounted.
To this end, Korean Patent Application Publication No. 10-2011-0085117 proposes a bulb-type LED lighting apparatus. As shown in FIG. 1a and FIG. 1b of the accompanying drawings, the bulb-type LED lighting apparatus includes LED circuit boards 10 having LEDs 11 mounted to a surface of each of the LED circuit boards 10. The LED lighting apparatus further includes a heat dissipating plate 20 and a heat dissipating unit 30 made of metal (for example, aluminum (Al)). Here, the LED circuit boards 10 are held in the heat dissipating unit 30 and the heat dissipating plate 20 is placed below the LED circuit boards 10.
Here, the heat dissipating unit 30 is shaped as a polygonal container, with inside and outside heat dissipating fins 33 and 34 formed inside and outside a polygonal heat dissipating frame 32 constituting the heat dissipating unit 30. Cover locking slits for holding protective covers 38 are formed along the outside heat dissipating fins 34, and circuit board seats 35 are formed on outside flat surfaces of the polygonal heat dissipating frame 32, so the LED circuit boards 10 can be seated on the respective circuit board seats 35.
Further, a connection cap 60 and a converter PCB 70 having respective air passing holes 61 and 71 are installed above the heat dissipating unit 30 at locations inside a base unit 40 connected to an external electric power source. To dissipate heat from the inside of the base unit 40 to the outside, air passing slits 42 are formed on the base unit 40.
In the conventional bulb-type LED lighting apparatus having the above-mentioned construction, the heat dissipating frame 32 of the heat dissipating unit 30 is formed as a single body having a hexagonal cross-section. Here, the sidewall of the heat dissipating frame 32 is closed, and the interior of the heat dissipating frame 32 communicates with the outside only via the air passing holes of the heat dissipating plate 20 installed in the lower end of the heat dissipating frame 32. Thus, although ambient cold air is introduced into the interior of the heat dissipating frame 32 via the air passing holes of the heat dissipating plate 20, the LED lighting apparatus may fail to efficiently dissipate heat from the interior of the heat dissipating frame 32 to the outside, so the LED lighting apparatus may not be efficiently cooled. Further, although heat dissipating plates are installed in the upper and lower ends of the heat dissipating frame 32 having the closed sidewall, the heat dissipating plates may stop the convective flows of air, so the LED lighting apparatus is problematic in that the interior of the heat dissipating frame 32 may reach a temperature of about 90° C.
Accordingly, the above-mentioned LED lighting apparatus cannot efficiently dissipate internal heat of the heat dissipating frame to the outside, and the heat dissipating function of the air passing holes fails to realize desired heat dissipating effects, thereby reducing the expected life span of the LED lighting apparatus.